Powder deposition to form pattern on light imaged photosensitive diazonium salt coating having salt of aromatic amine

ABSTRACT

A photosensitive composition improved in sensitivity by adding a salt of a compound represented by the general formula: ##STR1## (wherein R 1  and R 2  each represents a straight chain alkyl group, and X, Y and Z each represents H, a straight chain alkyl group or an alkoxy group, but two or more of X, Y and Z can not be H at the same time) to an aromatic diazonium salt which gets sticky upon exposure to light.

This is a division of application Ser. No. 279,849 filed July 2, 1981,now U.S. Pat. No. 4,377,630.

BACKGROUND OF THE INVENTION

This invention relates to a photosensitive composition and a patternforming process using such composition.

The interior side of the face plate of the color picture tube is coatedwith three different kinds of phosphor in dots or in stripes. Thisphosphor coat layer is formed in the following way. First, a mixedcoating material composed of a phosphor for the first color and aphotosensitive resin is applied on the interior side of the face plateand dried to form a coating film, and this layer is irradiated withultraviolet rays through the holes in a shadow mask. The ultravioletrays are irradiated to the position where the electron beams foreffecting emission of light from the phosphor hit, that is, the placewhere said phosphor is to be attached. The photosensitive resin at theirradiated portion is insolubilized, resulting in insolubilization ofthe entire layer in that portion. Then the layer is washed with asolvent, retaining the insolubilized portion alone on the face platewhile removing the other portion of the layer by dissolution. Then thesame operation as said above is performed with the layer formed from amixture of a phosphor for the second color and a photosensitive resin,and this is followed by the same operation by using a mixture of aphosphor for the third color and a photosensitive resin.

As appreciated from the foregoing explanation, the color picture tubephosphor surface forming process is complicated, and multiple times ofrepetition of wet coating, water washing and drying are required, sothat simplification of such process is quite desirable.

As an improvement on such process, some of the present inventors havepreviously proposed, in Japanese Laid-Open Patent Application No.126861/78, a method of forming the color picture tube phosphor surfacein a considerably simpler manner than the prior art. This method wasattained on the basis of a new finding that the photolytic product of anaromatic diazonium salt has an ability to accept powder particles, andit is characterized by (1) coating the inner surface of the face plateof a corlor picture tube with a photosensitive composition containing anaromatic diazonium salt as a photosensitive component and getting stickyby light exposure, thereby forming a thin coating layer on said surface,(2) subjecting said thin layer to patternwise exposure to make theexposed portion sticky, and (3) contacting the powder particles with theexposed thin layer to have said powder particles accepted by said thinlayer.

According to this method, mere repetition of exposure and powder contactis required for the phosphors of the second and third colors, and whenthe coating film is once formed, it is possible to form as many phosphorpatterns as desired. It is also possible to produce a black matrix byusing powder of a light-absorbing material such as, for example, carbonpowder.

This method, however, has a drawback that the processing time is ratherlong due to a somewhat lower sensitivity of the photosensitive componentthan the conventional photosensitive resins.

On the other hand, the following references are also known to show thestate of the art: British Pat. Nos. 1,103,864 and 1,103,865.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a process for forming apattern with said aromatic diazonium salt and a highly sensitivecomposition used in such process.

Another object of the present invention is to provide a photosensitivecomposition containing a salt of a compound represented by the generalformula: ##STR2## (wherein R₁ and R₂ are each a straight chain alkylgroup, X, Y and Z are each H, a straight chain alkyl group or an alkoxygroup, but two or more of X, Y and Z can not be H at the same time) andan aromatic diazonium salt which gets sticky upon light exposure, and aprocess for forming a pattern by using such composition.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The salt of a compound represented by the above-shown general formula ispreferably a hydrochloride-zinc chloride double salt. This is due to thefollowing reason. As mentioned in said Japanese Laid-Open PatentApplication No. 126861/78, if the coating film containing thephotosensitive component remains non-crystallized, powder might depositat the non-exposed part, too, when the powder is contacted with thecoating film, so that the coating film needs be crystallized. As for thearomatic diazonium salt used as photosensitive component, it isdesirable to employ a diazonium chloride-zinc chloride double saltbecause of its excellent crystallinity and high rate of powderdeposition. Said aromatic diazonium salt and a salt of a compound of theabove-shown general formula (hereinafter referred to as additive) areformed into a solution and such solution is applied on a substrate anddried to form a coating film. Thus, since two different salts exist inthe solution, it is preferable that they are anions of the same type,and for this reason, it is desirable that the additive is a double saltwith zinc chloride. Further, in crystallinity of the additive itself, ahydrochloride-zinc chloride double salt is more advantageous than othertypes of salt. It is of course possible to use other salts such as tinsalt, calcium salt or iron salt.

R₁ and R₂ in the shown general formula are preferably a methyl group oran ethyl group as they provide excellent crystallinity of the additiveitself. Methyl group is most preferred because of particularly highcrystallinity.

The alkyl group and alkoxy group represented by X, Y and Z preferablyhave not more than 2 carbon atoms for the same reason as said above(excellent crystallinity). Use of a substituent having 3 or more carbonatoms can produce the same sensitizing effect as provided when usingsaid group having not more than 2 carbon atoms, but in this case,crystallinity of the coating film formed is deteriorated, so that it ispreferable to use a group having not more than 2 carbon atoms as saidabove.

As the examples of such salts of the compounds of the above-showngeneral formula, there may be cited the following:

2,6-dimethyl-N,N-dimethylaniline hydrochloride zinc chloride double salt##STR3## 3,5-dimethyl-N,N-dimethylaniline hydrochloride zinc chloridedouble salt ##STR4## 2,4,6-trimethyl-N,N-dimethylaniline hydrochloridezinc chloride double salt ##STR5## 2,6-diethyl-N,N-dimethylanilinehydrochloride zinc chloride double salt ##STR6##3-methoxy-2,6-dimethyl-N,N-dimethylaniline hydrochloride zinc chloridedouble salt ##STR7## 3-ethoxy-2,6-dimethyl-N,N-dimethylanilinehydroxhloride zinc chloride double salt ##STR8##4-methoxy-2,6-dimethyl-N,N-dimethyl-N,N-dimethylaniline hydrochloridezinc chloride double salt ##STR9##4-ethoxy-2,6-dimethyl-N,N-dimethylaniline hydrochloride zinc chloridedouble salt ##STR10##

Among other examples are 3,5-dimethyl-4-ethoxy-N,N-dimethylanilinehydrochloride zinc chloride double salt,3,5-dimethyl-4-methoxy-N,N-dimethylaniline hydrochloride zinc chloridedouble salt, and 3,4,5-trimethoxy-N,N-dimethylaniline hydrochloride zincchloride double salt.

There are known several sensitizers which promote photolysis ofdiazonium salts, but all of these sensitizers are of the type whichmerely promotes decomposition of diazonium salts in a solution and suchsensitizers show no sensitizing effect in a solid phase state. Theadditive used in this invention is capable of promoting photolysis ofdiazonium salt in crystallized solid phase, and no such type of additivehas been known to date. Also, the additive of this invention hardlyinhibits crystal growth of diazonium salts.

The amount of the additive added is preferably within the range of 300-1wt%, more preferably 300-5 wt%, based on the weight of the aromaticdiazonium salt. Addition of the additive in an amount of 1 wt% or moreimproves the diazonium salt photolyzing efficiency, and addition in anamount of 5 wt% or more gives a greater improvement of the photolyzingefficiency. On the other hand, addition of the additive in excess of 300wt% results in a reduced crystallinity of the coating film. Two or moreadditives may be used in admixture.

As the aromatic diazonium salt constituting the photosensitive componentin the composition of this invention, there may be used, for example,those cited in afore-mentioned Japanese Laid-Open Patent Application No.126861/78 or the novel aromatic diazonium salts disclosed in ourseparate application. Exemplary of the former are the aromatic diazoniumchloride zinc chloride double salts such as 4-(dimethylamino)benzenediazonium chloride zinc chloride double salt,4-(diethylamino)benzenediazonium chloride zinc chloride double salt,4-(N-ethyl-N-hydroxyethylamino)benzenediazonium chloride zinc chloridedouble salt and 4-methoxybenzenediazonium chloride zinc chloride doublesalt; aromatic diazonium tetrafluoroborates such as4-(dimethylamino)benzenediazonium borohydrofluoride and2-methoxybenzenediazonium borohydrofluoride; and aromatic diazoniumacidic sulfates such as 4-(dimethylamino)benzenediazonium sulfate, whilethe latter includes 2-methyl-4-(dimethylamino)benzenediazonium chloridezinc chloride double salt, etc.

Among said salts, zinc chloride double salts are preferred forcrystallizing the coating film as said above. It is particularlypreferable to use 4-(dimethylamino)benzenediazonium chloride zincchloride double salt, and in case of using two or more salts inadmixture, it is desirable to add said 4-(dimethylamino)benzenediazoniumchloride zinc chloride double salt as one of the salts to be mixed.

It has been already proposed to blend an organic polymer compound and/ora surfactant in the photosensitive component for the purpose ofimproving coatability when forming a thin layer with the photosensitivecomponent according to this invention, and use of such blendedphotosensitive component is desirable in this invention, too. Theorganic polymer compounds recommendable for use in this invention forsaid purpose include gum arabic, polyvinyl alcohol, polyacrylamide,poly-N-vinylpyrrolidone, hydroxypropylmethyl cellulose, alginic acid,propylene glycol esters of alginic acid, acrylamide-diacetoacrylamidecopolymer and methylvinyl ether-maleic anhydride copolymer. Theseorganic polymer compounds are preferably used in an amount of 0.5-500wt% based on the aromatic diazonium salt. The surfactant is preferablyused in an amount of 0.01-1 wt%.

In the present invention, a pattern is formed by applying a solution ofsaid composition on a substrate, drying it to form a coating film,subjecting this coating film to light exposure of a predeterminedpattern to make the exposed part sticky, then contacting powder withthis coating film so that powder deposits at the exposed part whileremoving the rest of powder by a suitable means such as air spray, andthe process after exposure is repeated for the second and third powders.It is thereby possible to form a high-sensitivity pattern with severaldifferent kinds of powder.

The powder used in this invention is one having a mean particle size ofabout 0.01 to about 100 μm. In case of using a phosphor or apigment-attached phosphor, it is preferable to use powder having a meanparticle size of about 4-15 μm. It is more desirable to use a phosphorsurface treated with Zn(OH)₂ or the like such as shown in a patentapplication filed separately by a part of the present inventors.

That the thus formed phosphor coating layer can be fixed by contactingit with an alkaline material vapor such as ammonia gas is taught inafore-mentioned Japanese Laid-Open Patent Application No. 126861/78 andother literatures, and such fixing procedures can be employed in thisinvention as well.

It is also possible to use the fixing method shown in Japanese Laid-OpenPatent Application No. 32332/80 filed by a part of the presentinventors. According to this method, a powdery material which forms awater-insoluble or sparingly water-soluble solid material upon reactionwith the product from a photolytic reaction of an aromatic diazoniumsalt is applied after or during formation of the powder (such asfluorescent substance) coat layer. Therefore, such powdery material forfixing depends on the type of the diazonium salt used. For example, incase the diazonium salt used is a zinc chloride double salt, thephotolytic product is zinc chloride, and as the powder material forfixing, there may be used alkali metal hydroxide, alkaline earth metalhydroxide, alkali metal oxide, alkaline earth metal oxide, alkali metalcarbonate, bicarbonate or oxalate, ammonium carbonate, ammonium oxalate,etc. In case the diazonium salt is an acidic sulfate, the photolyticproduct is sulfate, and hence alkaline earth metal hydroxide, alkalineearth metal oxide, alkali metal carbonate, nitrate, acetate, etc., maybe used as the powdery material for fixing.

The present invention will be further described below by referring tothe Examples thereof.

EXAMPLE 1

50 g of 2,6-dimethylaniline was suspended in 124 cc of water, followedby dropwise addition of 105 g of dimethyl sulfate at a temperature below20° C. Then 132 g of an aqueous 30% sodium hydroxide solution was addedto dimethylize the amino group. The resulting N,N-dimethyl compound wasdissolved in hydrochloric acid and added with 4-fold molar amount ofzinc chloride to precipitate a double salt. It was recrystallized fromdilute hydrochloric acid to obtain the salt of formula I. M.p.:155°-156° C.; amount of zinc: 12.3% (calculated: 12.9%) (the amount ofzinc in this and following Examples was measured by EDTA chelatetitration); NMR (chemical shift): 3.3 ppm, 2.5 ppm, 7.2 ppm.

EXAMPLE 2

The same treatment as Example 1 was carried out by using3,5-dimethylaniline instead of 2,6-dimethylaniline to obtain the salt offormula II. M.p.: 125°-126° C.; amount of zinc: 12.8% (calculated:12.9%); NMR (chemical shift): 3.2 ppm, 2.3 ppm, 7.2 ppm.

EXAMPLE 3

The same treatment as Example 1 was carried out by using2,4,6-trimethylaniline to obtain the salt of formula III. M.p.:187°-189° C.; amount of zinc: 12.1% (calculated: 12.2%); NMR (chemicalshift): 2.8 ppm, 2.1 ppm, 2.0 ppm, 6.6 ppm.

EXAMPLE 4

2,6-diethylaniline was suspended in water and added dropwise withdimethyl sulfate at room temperature to effect dimethylation, and thesolution was distilled to obtain 2,6-diethyl-N,N-dimethylaniline. Thiswas dissolved in a hydrochloric acid solution and admixed with zincchloride to synthesize 2,6-diethyl-N,N-dimethylaniline hydrochloridezinc chloride double salt of formula IV. Amount of zinc: 11.6%(calculated: 11.5%); infrared absorption spectra (KBr tablet method):3070 cm⁻¹, 1450 cm⁻¹, 1380 cm⁻¹, 810 cm⁻¹, 560 cm⁻¹.

EXAMPLE 5

40 ml of 2,6-dimethyl-N,N-dimethylaniline was dissolved in 88 ml ofconcentrated sulfuric acid at a temperature below 15° C., followed bydropwise addition of 35 ml of concentrated nitric acid by maintainingthe temperature below 15° C. Thereafter, the mixture was reacted for onehour, poured into cold water and then neutralized with sodium carbonate,whereby 3-nitro-2,6-dimethyl-N,N-dimethylaniline was precipitated in theform of crystals. The produced nitro compound was reduced, diazotizedand then pyrolyzed to obtain 3-hydroxy-2,6-dimethyl-N,N-dimethylaniline.This phenol compound was dissolved in an alkaline solution and treatedwith excess dimethyl sulfate at 40°-45° C. The resulting3-methoxy-2,6-dimethyl-N,N-dimethylaniline was dissolved in hydrochloricacid and then admixed with double molar amount of zinc chloride toprecipitate a double salt. It was recrystallized from dilutehydrochloric acid to obtain the salt of formula V. M.p.: 162°-165° C.,amount of zinc: 11.8% (calculated: 11.4%); infrared absorption spectra:3100 cm⁻¹, 1450 cm⁻¹, 1260 cm⁻¹, 1070 cm⁻¹, 820 cm⁻¹, 1600 cm⁻¹ ; NMR(chemical shift): 3.4 ppm, 3.9 ppm, 2.4 ppm, 2.5 ppm, 7.1 ppm, 7.2 ppm,7.0 ppm, 7.3 ppm.

EXAMPLE 6

3-hydroxy-2,6-dimethyl-N,N-dimethylaniline obtained in the same way asExample 5 was dissolved in an alkaline solution and admixed dropwisewith diethyl sulfate by maintaining the temperature at 50°-60° C. tosynthesize 3-ethoxy-2,6-dimethyl-N,N-dimethylaniline. It was dissolvedin hydrochloric acid and admixed with double molar amount of zincchloride to precipitate a double salt. Recrystallization thereof fromdilute hydrochloric acid gave the salt of formula VI. M.p.: 164°-165°C.; amount of zinc: 11.1% (calculated: 10.9%); infrared absorptionspectra: 3100 cm⁻¹, 1610 cm⁻¹, 1460 cm⁻¹, 1270 cm⁻¹, 1070 cm⁻¹, 820 cm⁻¹; NMR (chemical shift): 3.4 ppm, 2.4 ppm, 2.5 ppm, 1.4 ppm, 1.3 ppm, 1.5ppm, 4.0 ppm, 4.1 ppm, 3.9 ppm, 4.2 ppm, 7.1 ppm, 7.2 ppm, 6.9 ppm, 7.3ppm.

EXAMPLE 7

25 g of 3,5-dimethylphenol was dissolved in 200 g of an aqueous 5%sodium hydroxide solution, and in this solution were added and dissolved1 g of hypo and 20 g of sodium nitrite. Then an aqueous solution formedby dissolving 27 ml of concentrated sulfuric acid in 80 ml of water wasadded dropwise into the abovesaid solution by maintaining thetemperature below 7° C., causing precipitation of4-nitroso-3,5-dimethylphenol. The obtained nitroso compound wasdissolved in an alkaline solution (caustic soda) and admixed dropwisewith dimethyl sulfate while maintaining the temperature at 40°-45° C. toeffect etherification. Then the nitroso group was reduced to synthesize4-methoxy-2,6-dimethylaniline. The produced aniline compound wassuspended in water and dimethyl sulfate was acted at room temperature todimethylize the amino group. Resulting4-methoxy-2,6-dimethyl-N,N-dimethylaniline was dissolved in hydrochloricacid and admixed with double molar amount of zinc chloride toprecipitate a double salt. It was recrystallized from dilutehydrochloric acid to obtain the salt of formula VII. M.p.: 45°-47° C.;infrared absorption spectra: 3100 cm⁻¹, 1600 cm⁻¹, 1460 cm⁻¹, 1310 cm⁻¹,1160 cm⁻¹, 1060 cm⁻¹, 860 cm⁻¹ ; amount of zinc: 17.4% (calculated:18.4%).

EXAMPLE 8

4-nitroso-3,5-dimethylphenol synthesized after the manner of Example 7was dissolved in an alkaline solution and admixed dropwise with diethylsulfate at 50°-60° C. to etherify the phenol. Then the nitroso group wasreduced to synthesize 4-ethoxy-2,6-dimethylaniline. This anilinecompound was suspended in water and dimethyl sulfate was acted at roomtemperature to dimethylize the amino group. Resulting4-ethoxy-2,6-dimethyl-N,N-dimethylaniline was dissolved in hydrochloricacid and admixed with double molar amount of zinc chloride toprecipitate a double salt. By recrystallization from dilute hydrochloricacid, the salt of formula VIII was obtained. M.p.: 42°-43° C.; infraredabsorption spectra: 3100 cm⁻¹, 1600 cm⁻¹, 1460 cm⁻¹, 1310 cm⁻¹, 1160cm⁻¹, 1060 cm⁻¹, 840 cm⁻¹ ; amount of zinc: 16.5% (calculated: 17.7%).

EXAMPLE 9

An aqueous solution having a composition comprising 80 g of a 0.5%aqueous solution of a propylene glycol alginate ester which is awater-soluble polymer compound, 3.2 g of4-(dimethylamino)benzenediazonium chloride zinc chloride double saltused as photosensitive component, 0.7 g of the additive of formula I and20 g of water was coated on a glass substrate by spin coating to form a0.5 μm thick photosensitive layer.

This layer was exposed to the ultraviolet rays from a 500 W super-highpressure mercury arc lamp at a distance of 90 cm from said layer throughan aperture mask having a predetermined pattern for a period of 63seconds, and then a phosphor was placed thereon. The phosphor depositedon the irradiated portion alone. Likewise, the second and thirdphosphors were deposited by the second and third exposure operations.

For the purpose of comparison, the same treatment was performed by usingthe same photosensitive composition save the additive. In this case, theexposure time required for attaining a sufficient amount of phosphordeposit was 85 seconds.

EXAMPLES 10 AND 11

When the amounts of the photosensitive component (diazonium salt) andthe additive were changed as shown in Table 1, the exposure timerequired for giving a sufficient amount of phosphor deposit was as shownin Table 1.

                  TABLE 1                                                         ______________________________________                                        Example                                                                              Photosensitive Additive Exposure time                                  No.    component (g)  (g)      (sec)                                          ______________________________________                                        10     2.7            1.2      56                                             11     2.0            1.75     50                                             ______________________________________                                    

EXAMPLES 12, 13 AND 14

When the same treatments as in Examples 9, 10 and 11 were performed byusing the salt of formula II instead of the salt of formula I asadditive, the substantially same results were obtained.

EXAMPLE 15

0.7 g of the additive of formula III and 3.2 g of4-(dimethylamino)benzenediazonium chloride zinc chloride double saltwere dissolved in 80 g of a 0.5% aqueous solution of propylene glycolalginate ester, and this solution was further admixed with 20 g of waterand then applied on a glass substrate to form a 0.5 μm thick coatingfilm. This coating film was exposed to a 500 W super-high pressuremercury arc lamp from a distance of 90 cm through a mask for a period of63 seconds, and then a phosphor powder was contacted therewith and theunnecessary phosphor was removed by air spray to obtain a phosphorpattern corresponding to the exposed portion.

EXAMPLE 16

An aqueous solution having a composition comprising 3.2 g of4-(dimethylamino)benzenediazonium chloride zinc chloride double saltforming the photosensitive component, 0.7 g of the material of formulaIV, 80 g of a 0.5% aqueous solution of propylene glycol alginate esterwhich is a water-soluble polymer compound and 20 g of water was coatedon a glass substrate by rotary coating to form a 0.5 μm thickphotosensitive layer. This layer was exposed to the ultraviolet raysfrom a 500 W super-high pressure mercury arc lamp from a distance of 90cm through an aperture mask having a predetermined pattern for a periodof 63 seconds. When a phosphor was applied thereto immediately, saidphosphor deposited at the irradiated portion alone.

By way of comparison, the same treatment was conducted by using the samephotosensitive composition save said additive. In this case, theexposure time required for providing a sufficient amount of phosphordeposit was 85 seconds.

EXAMPLE 17

An aqueous solution having a composition comprising 80 g of a 0.5%aqueous solution of propylene glycol alginate ester which is awater-soluble polymer compound, 3.3 g of4-(dimethylamino)benzenediazonium chloride zinc chloride double salt asphotosensitive component, 0.33 g of the additive of formula V and 20 gof water was coated on a glass substrate by spin coating to form a 0.5μm thick photosensitive layer.

This layer was exposed to the ultraviolet rays from a 500 W super-highpressure mercury arc lamp from a distance of 90 cm through an aperturemask having a predetermined pattern for a period of 63 seconds, and thena phosphor was applied thereto, whereby the phosphor was allowed todeposit at the irradiated portion alone. The second and third phosphorswere deposited likewise by the second and third exposure operations.

For comparison, the same treatment was performed by using the samephotosensitive composition save the additive. In this case, the exposuretime required for depositing a sufficient amount of phosphor was 85seconds.

EXAMPLES 18 AND 19

When the amounts of the diazonium salt (photosensitive component) andthe additive were changed as shown in Table 2, the exposure timerequired for giving a sufficient phosphor deposit was as shown in Table2.

                  TABLE 2                                                         ______________________________________                                        Example                                                                              Photosensitive Additive Exposure time                                  No.    component (g)  (g)      (sec)                                          ______________________________________                                        18     3.3            0.5      56                                             19     3.3            0.7      50                                             ______________________________________                                    

EXAMPLE 20

0.33 g of the additive of formula VI and 3.3 g of4-(dimethylamino)benzenediazonium chloride zinc chloride double saltwere dissolved in 80 g of a 0.5% aqueous solution of propylene glycolalginate ester, and this solution was further added with 20 g of waterand applied on a glass substrate to form a 0.5 μm thick coating film. Itwas exposed through a mask for 63 seconds by using a 500 W super-highpressure mercury arc lamp from a distance of 90 cm, and then a phosphorpowder was contacted therewith and the unnecessary phosphor was removedby air spray to obtain a phosphor pattern corresponding to the exposedpart.

EXAMPLE 21

When the same treatment as in Example 17 was carried out by using theadditive of formula VII, the substantially same results were obtained.

EXAMPLES 22 AND 23

When the same treatment as in Example 17 was performed by using theadditive of formula VIII and changing the amount of said additive to 1%by weight (Example 22) and 5% by weight (Example 23) based on the weightof the photosensitive component, and substantially same results wereobtained, with the exposure time required being 81 seconds (Example 22)and 72 seconds (Example 23).

EXAMPLE 24

The same synthesis as in Example 5 was carried out by using2,6-dimethyl-N,N-diethylaniline to obtain3-methoxy-2,6-dimethyl-N,N-diethylaniline hydrochloride zinc chloridedouble salt. When the treatment of Example 17 was repeated by using thisdouble salt, there were obtained the substantially same results.

What is claimed is:
 1. A process for forming a pattern of powder coatlayer comprising the steps of coating a substrate with a photosensitivecomposition containing an aromatic diazonium salt which gets sticky uponexposure to light and a salt of a compound represented by the generalformula: ##STR11## (wherein R₁ and R₂ each represents a straight chainalkyl group, and X, Y and Z each represents H, a straight chain alkylgroup or an alkoxy group, but two or more of X, Y and Z can not be H atthe same time) to form a thin coat layer on said substrate, subjectingsaid thin layer to pattern light exposure to make the exposed partsticky, and contacting the powder particles with the exposed thin layerto have the powder deposited on the exposed part.
 2. The processaccording to claim 1, wherein the amount of a salt of a compoundrepresented by the above-shown general formula is within the range of300-1% by weight based on the aromatic diazonium salt.
 3. The processaccording to claim 1, wherein R₁ and R₂ in the above shown generalformula are each a straight chain alkyl group having two or less carbonatoms.
 4. The process according to claim 3, wherein R₁ and R₂ in theabove-shown general formula are each a methyl group.
 5. The processaccording to any of claims 1 to 4, wherein the straight chain alkylgroup represented by one or more of X, Y and Z in the above-showngeneral formula has two or less carbon atoms.
 6. The process accordingto any of claims 1 to 4, wherein the alkoxy group represented by one ormore of X, Y and Z in the above-shown general formula has two or lesscarbon atoms.
 7. The process according to any of claims 1 to 4, whereinthe salt of a compound represented by the above-shown general formula isa hydrochloride zinc chloride double salt.
 8. The process according toany of claims 1 to 4, wherein the salt of a compound represented by theabove-shown general formula is a salt of at least one compound selectedfrom the group consisting of 2,6-dimethyl-N,N-dimethylaniline,3,5-dimethyl-N,N-dimethylaniline, 2,4,6-trimethyl-N,N-dimethylaniline,2,6-diethyl-N,N-dimethylaniline,3-methoxy-2,6-dimethyl-N,N-dimethylaniline,3-ethoxy-2,6-dimethyl-N,N-dimethylaniline,4-methoxy-2,6-dimethyl-N,N-dimethylaniline and4-ethoxy-2,6-dimethyl-N,N-dimethylaniline.
 9. The process according toclaim 8, wherein the salt of a compound represented by the above-showngeneral formula is a hydrochloride zinc chloride double salt.
 10. Theprocess according to any of claims 1 to 4, wherein said photosensitivecomposition further contains an organic polymer compound in an amountwithin the range of 0.5-500% by weight based on the aromatic diazoniumsalt.
 11. The process according to claim 10, wherein the organic polymercompound is at least one member selected from the group consisting ofgum arabic, polyvinyl alcohol, polyacrylamide, poly-N-vinylpyrrolidone,hydroxypropylmethyl cellulose, alginic acid, propylene glycol ester ofalginic acid, acrylamide-diacetoacrylamide copolymer and methylvinylether-maleic anhydride copolymer.
 12. The process according to any ofclaims 1 to 4, wherein the thin layer of photosensitive composition iscrystalline.